In general, color films are pretty tolerant, you could easily shoot it at 800 and not loose much shadow detail, and you could go higher with some push processing.

But shooting your Portra 400 at 160, 200, 800 or whatever is not the same as working with a film which has those box speeds.

If you want the best overall results, shoot it at 400, if you want more detail at the low or high ends, over expose or under expose accordingly. But keep in mind that when you do that you're sacrificing some at the other end.

I routinely shoot my Portra 400 as I said above, which is really shooting at more like 200. For Portra 160 I usually set the meter or camera at 125.

Color neg is almost always better with a bit more exposure. ISO is a carefully defined speed point, but that does NOT mean it is the optimum exposure index for best quality. For that matter I expose most black and white films at lower EIs than the box ISO speed too.

"Best overall results" will honestly be obtained with Portra 400 at something less than box speed. Same with almost any C41 film. That doesn't mean box speed isn't good. It is.

If you under-expose, you could lose satuation which results in a drab look. You may also get colour shifts if you need to develop it for longer.

A small amount of over-exposure may increase saturation but if you go too far it won't look good either.

Generally, I shoot most films at box speed, especially colour. It is best for predictability and consistency of the results.

Do experiment, by all means, but bear in mind that C41 development is prone to slight variations, even if you use a pro lab. If you develop it yourself, you may get very varying results between the batches.

If you are going to shoot under varying light, it's best to bring slow, normal and fast film, and to use a good lens with a large aperture span.

True for slide film, not true at all for color neg. Most color neg films benefit from more exposure than using box speed will give. The intent of overexposing has nothing to do with saturation. It reduces effective "grain" (all the silver is actually bleached out in processing so "grain" is really just a convenient and familiar term from B&W) slightly lower contrast, and gobs of shadow detail which you can choose to print or not.

It's almost impossible to overexpose color neg film so much that you won't get good results and 1/2 to 1 stop more than box speed usually yields slightly better-for-most-purposes results.

I did read a test recently where someone had shot Porta 400 at different ISOs. It concluded that 400 and 320 gave the best results, but if you go higher or lower you start getting undesirable effects. It was backed up with negative samples that seemed to support this conclusion.

If your'e happy with the film at I.S.O. 400, why try to be clever ? Kodak know what the optimum speed of their products are to get the best results, I would only consider adjusting the film speed rating if I was unhappy with the results.

I'm confused by this post, if you are primarily planning to slightly under expose the film, then why would use use an EI of 160 on a 400 speed film, that would OVER expose it. So I'm confused.

Sorry about the confusion, the overexposure and look of 400 at 160 were independent statements.

Originally Posted by Jaf-Photo

If you are going to shoot under varying light, it's best to bring slow, normal and fast film, and to use a good lens with a large aperture span.

The problem is, I shoot medium format and mostly in not so great light. So I HAVE to stop down a bit to get high enough shutter speeds to hand hold. Also, not a huge fan of 800 speed films due to the grain (for colour). Therefore was trying to find out what my options are.

Sorry about the confusion, the overexposure and look of 400 at 160 were independent statements.

The problem is, I shoot medium format and mostly in not so great light. So I HAVE to stop down a bit to get high enough shutter speeds to hand hold. Also, not a huge fan of 800 speed films due to the grain (for colour). Therefore was trying to find out what my options are.

There is some confusion here. Shooting at 160 and overexposure are the same (perhaps you mean underexposure and 160 were ind. statements) ; and you have to OPEN up not stop down to get higher shutter speeds to hand hold.

I am just having a bad day explaining what I intend to convey. What I meant was, since I shoot 120, the DoF is much thinner compared to 135. Therefore, I have to stop down to get a DoF that makes sense, which in turn slows down the shutter. So, now, to get hand held speeds, I have to up the film speed. Does that make sense?

Yeah, I did mean 160 and underexposure are independent statements. Silly me

Under exposing and bad lighting conditions are not a good combination.
You may want to consider a camera support, or else learn to brace the camera against solid objects, or, try Portra 800.
If you've not used it, you may be surprised at the quality.

Sorry about the confusion, the overexposure and look of 400 at 160 were independent statements.

The problem is, I shoot medium format and mostly in not so great light. So I HAVE to stop down a bit to get high enough shutter speeds to hand hold. Also, not a huge fan of 800 speed films due to the grain (for colour). Therefore was trying to find out what my options are.

Portra 800 is a great option. If you have detachable film backs you could always load a couple with different film speeds and change as needed.